By Sam Kim SEOUL, Nov. 24 (Yonhap) -- By mounting a deadly artillery attack on South Korea, North Korea seeks to bolster the military profile of its fledgling heir apparent and drive regional tensions to a level favorable for extracting concessions, officials and analysts say.

"We see it as a hard-lined plot aimed at toughening the internal unity and succession course by making a display of the leadership of Kim Jong-un, (the third son of leader Kim Jong-il,)" South Korean Defense Minister Kim Tae-young told lawmakers Wednesday.

Tuesday's attack, which prompted South Korea to shoot back, killed two South Korean marines after dozens of shells landed on the border island of Yeonpyeong, home to at least 1,500 civilians.

The shelling, immediately denounced by both South Korea and the United States, came after North Korea sent the world into a state of alarm earlier this month by unveiling a highly sophisticated plant for enriching uranium, a new route to building nuclear bombs.

It was also the first inter-Korean clash since North Korean leader Kim Jong-il unveiled his youngest son as a four-star military general in September. North Korean officials describe the 27- or 28-year-old as successor to his 68-year-old father.

"Kim Jong-un wants to show that he is tough, thus winning support in the military," Andrei Lankov, a North Korea expert at Seoul's Kookmin University, said in an email interview.

Little is known about the character of the Swiss-educated man, who, according to North Korean media Tuesday, toured a soy sauce factory and a medical school with his father in Pyongyang.

The official media typically do not give the exact time of field inspections by their leaders, but the reports helped dispel growing questions about their whereabouts in the midst of one of the worst armed clashes since the 1950-53 Korean War ended in a truce.

"The display of such belligerent behavior suggests that Kim junior may be flexing his muscles as a way of shoring up capital within the North Korean political elite, and particularly the military," IHS Global Insight Asia analyst Sarah McDowall said in a release.

Yang Moo-jin, a professor at the University of North Korean Studies in Seoul, described the attack as "the result of a meticulous calculation."

"North Korea is trying to increase the stability in the region in response to tightening pressure by the U.S., South Korea and Japan," he said by phone.

Yang said the North appears to be discouraged by the U.S. response to its unveiling of a uranium enrichment plant in Yongbyon, which Pyongyang says contains 2,000 centrifuges.

Centrifuges can be used to produce highly enriched uranium, an additional means of nuclear arms development for North Korea, which has already tested two plutonium-based bombs.

Visiting South Korea on the heels of the revelation, Stephen Bosworth, the top U.S. point man on North Korea, on Monday downplayed the development as "not a crisis," even though he described it as "provocative" and "disappointing."

Yang said, "North Korea probably felt it had to do something more drastic to make the situation more unstable."

Pyongyang admitted to a clandestine uranium program in 2002. The unveiling of an enrichment plant came as the impoverished country bolstered its call for the restart of disarmament-for-aid six-nation talks that also involve the U.S., Japan, China, Russia and South Korea.

"It seems that the North Korean government decided that it is time to raise stakes again," Lankov said. "(The shelling) is their usual tactics: first they stage provocations and drive tensions high and then suggest to start negotiations in order to extract payments for solving the problems they themselves created."

"The North is driving the situation to the worst level possible. It will soon seek to allure dialogue," he said. "This is the most extreme level of brinkmanship we have seen from Pyongyang."

"The shelling only darkens the prospect for the resumption of six-party talks," Kim Seong-joo, a political science professor at Seoul's Sungkyunkwan University, said.

The talks have not been held since late 2008. Since South Korea blamed North Korea for sinking its Cheonan warship and killing 46 sailors in March near the Yellow Sea border, Seoul has called on Pyongyang to take steps to account for the attack before reopening the talks. Pyongyang denies any role and has threatened war for retaliatory measures by Seoul.